Infrastructure at your Service

All Posts By

Franck Pachot

Franck Pachot

Oracle Rolling Invalidate Window Exceeded(3)

By | Oracle | No Comments

By Franck Pachot . This extends a previous post (Rolling Invalidate Window Exceeded) where, in summary, the ideas were: When you gather statistics, you want the new executions to take into account the new statistics, which means that the old execution plans (child cursors) should be invalidated You don’t want all child cursors to be immediately invalidated, to avoid an hard parse storm, and this is why this invalidation is rolling: a 5 hour window…

Read More
Franck Pachot

Oracle DB on Azure with Multitenant Option

By | Cloud | 3 Comments

By Franck Pachot . If you want to run an Oracle Database in the Microsoft Azure cloud, you will install it yourself on a VM. And then, you can expect the same as when you install it in your premises, in a virtual environment. Except that Oracle makes it two times more expensive by accepting to license the processor metric on vCPUs at the condition that the Intel core factor is not applied. And in…

Read More
Franck Pachot

Grafana, SQL and IN() list for multi-value variable

By | Database Administration & Monitoring | No Comments

By Franck Pachot . I’ve recently looked at Grafana. Pros: it is really nice, I mean aesthetically. If you want to build a dashboard for your boss, or put it on a large screen in the open space, that’s beautiful. Cons: not mature. I’m working for years with technology that works. When I have a problem, I find the solution (blog posts, forums, mailing lists, support notes)… But with modern software, the first problems I…

Read More
Franck Pachot

PostgreSQL on Linux: what is cached?

By | Postgres | No Comments

By Franck Pachot . In a recent tweet I wanted to highlight the importance of knowing what you measure with pgbench, because looking at “Transactions per second” without knowing if you are in shared buffer cache hits, or filesystem cache hit, or storage cache hit, or physical read… is just meaningless: When you run the #postgres builtin pgbench, you should know: – the size of the dataset on disk, about 15MB x scale – the…

Read More
Franck Pachot

Learn ODA on Oracle Cloud

By | Oracle | No Comments

By Franck Pachot . You want to learn and practice your ODA command line and GUI without having an ODA at home? It should be possible to run the ODA image on VirtualBox but that’s probably a hard work as it is tied to the hardware. About the configuration, you can run the Oracle Appliance Manager Configurator on your laptop but I think it is not compatible with the latest odacli. However, for a long…

Read More
Franck Pachot

Google Cloud SQL Insights: ASH, plans and statement tagging

By | Cloud, Postgres | No Comments

By Franck Pachot . Looking at database performance has always been necessary to optimize the response time or throughput, but when it comes to public cloud where you are charged by resource usage, performance tuning is critical for cost optimization. When looking at host metrics, you see only the symptoms and blindly guess at some solutions: add more vCPU if CPU usage is high, more memory if I/O wait is high. And this can be…

Read More
Franck Pachot

19c serverless logon trigger

By | Oracle | No Comments

By Franck Pachot . I thought I already blogged about this but can’t find it. So here it is, with a funny title. I like to rename oracle features by their user point of view (they are usually named from the oracle development point of view). This is about setting session parameters for Oracle connections, directly from the connection string, especially when it cannot be set in the application (code) or in the DB server…

Read More
Franck Pachot

Pressure Stall Information on Autonomous Linux

By | Database Administration & Monitoring | No Comments

By Franck Pachot . The Linux metrics that are usually considered for performance monitoring and troubleshooting have many drawbacks and frequent misinterpretations. The recent kernels provide PSI (Pressure Stall Information) which is not enabled by default in Oracle Linux “unbreakable” kernel. However, the kernel is compiled with it. Here is how to enabled it in a newly create Autonomous Linux instance (the Oracle Cloud Linux ,based on OEL 7.9, with no-downtime patching) Check PSI availability…

Read More
Franck Pachot

Google Spanner – SQL compatibility

By | Cloud | No Comments

By Franck Pachot . I have posted, a long time ago, about Google Spanner (inserting data and no decimal numeric data types) but many things have changed in this area. There is now a NUMERIC data type and many things have improved in this distributed SQL database, improving a bit the SQL compatibility. gcloud I can use the Cloud Shell, which is very easy – one click fron the console – but here I’m showing…

Read More
Franck Pachot

Optimizer Statistics Gathering – pending and history

By | Oracle | No Comments

By Franck Pachot . This was initially posted to CERN Database blog on Wednesday, 12 September 2018 where it seems to be lost. Here is a copy thanks to web.archive.org Demo table I create a table for the demo. The CTAS gathers statistics (12c online statistics gathering) with one row and then I insert more rows: 10:33:56 SQL> create table DEMO as select rownum n from dual; Table DEMO created. 10:33:56 SQL> insert into DEMO…

Read More